What rights do overbook fliers have? Not many.

Ben Mutzabaugh , USA TODAY , WUSA5:43 PM. PDT April 10, 2017

A United Airlines aircraft passes by a Continental Airlines aircraft as it taxis to takeoff from the runway of Ronald Reagan National Airport August 16, 2006 in Washington, DC. (Photo by Alex Wong/Getty Images) (Photo: Alex Wong, 2006 Getty Images)

United Airlines found itself at the center of controversy Monday after a video posted on Facebook showed a passenger being forcibly removed from an overbooked flight Sunday at Chicago’s O’Hare International Airport.

Several passengers reacted with horror as the man was pulled out of his seat and dragged toward the front of the plane by unidentified personnel. The flight from Chicago O'Hare to Louisville was operated by United Express affiliate Republic Airlines.

United confirmed that a passenger had been taken off Flight 3411 on Sunday in Chicago, with CEO Oscar Munoz apologizing and pledging to “conduct our own detailed review of what happened.”

The situation arose in part because United needed to get crewmembers onboard the sold-out flight so that they could get to Louisville to work a “downline connection,” said United spokesman Jonathan Guerin.

But the video has made headlines across the country, giving United an unwanted public relations black eye, just two weeks after it was exposed to criticism for denying boarding to two girls traveling on a guest pass because they were wearing leggings. Making it worse was that the passenger in this case had already boarded the flight.

“Once you’re offloading passengers who’ve already boarded so that you can get employees on the flight, you’d think they’d do just about anything to avoid that,” said Seth Kaplan, editor of the Airline Weekly trade publication.

Others echoed the sentiment that United probably could’ve handled the situation better.

“I’ve seen a lot in my 40 years covering and working for the airline industry, but this is historically bad public relations,” says George Hobica, president of Airfarewatchdog. “The burning question is why did they wait until everyone was seated before realizing they needed to move employees?”

As for passengers, they have surprisingly few rights when flights are “overbooked.”

Federal regulations do not prevent carriers from selling more seats than a flight can accommodate, a practice the airline industry says allows carriers to try to fill planes despite the number of no-shows that they can expect on any given flight.

Typically, airlines will ask for volunteers on oversold flights, promising some sort of compensation in return for taking a different flight. If few volunteer, carriers typically will keep increasing their offers until enough fliers agree to take another flight.

If not enough volunteers are found, the airline has the power to decide who gets “bumped” off the flight, though that typically happens before boarding.

Carriers spell this out in the “contract of carriage” that customers are bound to when they buy their tickets. But few fliers ever read that fine print, and such contracts don't always specify a clear order for such situations.

The Department of Transportation does have clear guidance about compensation due to fliers "involuntarily denied boarding," and that can pay off in the case of a significant inconvenience. For example, an involuntarily bumped traveler who arrives to his final destination more than four hours late is entitled to an amount worth 400% of his one-way fare (capped at a maximum of $1,350).

In the event there are not enough volunteers – as was the case with Sunday’s Flight 3411 – United's contract says preference will be given to “Qualified Individuals with Disabilities, unaccompanied minors under the age of 18 years, or minors between the ages of 5 to 15 years who use the unaccompanied minor service ….”

Beyond that, United does not spell out a hard and fast rule. Instead, the airline says only that “the priority of all other confirmed passengers may be determined based on a passenger’s fare class, itinerary, status of frequent-flier program membership, and the time in which the passenger presents him/herself for check-in without advanced seat assignment.”

Regardless, industry observers said they were surprised the situation unfolded the way it did for United.

“United could have easily avoided this historically bad public relations disaster had they increased the bumping compensation offer, either before boarding or once boarded,” says Hobica. “Whatever it cost -- $1,000, $2,000, $3,000 -- would have been far cheaper than the cost to its reputation and the loss of business. You can be sure that passengers, at least this week, will choose any other airline to get where they're going.”